Idea evaluation is a critical activity in the creative process due to its role in making a decision about what idea(s) should be developed further and implemented, or whether more ideas should be generated. Confidence in the correctness of the evaluation plays a key role in making that decision. Emerging evidence suggests that inner speaking, the talking that we do inside our own minds, can have an influence on creative thinking through its self-regulatory function. However, how self-regulation by inner speaking influences confidence during idea evaluation specifically is an open scientific problem. To explore this, an experiment was conducted with a within-subject design (n = 152). Each participant was asked to evaluate and rank three sets of ideas, which varied in the number of ideas presented, from least to most creative. After evaluating each set of ideas participants self-reported the frequency of positive and negative events, the frequency of self-critical, self-reinforcing, self-managing and socially assessing inner speaking they experienced during idea evaluation, and the confidence they had in their evaluation. The results showed that the effects of evaluating varying numbers of ideas on the frequency of positive and negative events causes variation in the frequency of self-critical, self-reinforcing, and self-managing inner speaking; and that the effects of increased negative events on increased self-critical and decreased self-reinforcing inner speaking negatively influenced the confidence participants had in their evaluation. Herewith, this study contributes new insights into how self-regulation by inner speaking influences confidence during idea evaluation.